I just dropped all my gold on the silver box, "Great Box". I purchased 3 of these.
The ultra box is worse than the great box, the great box is nice. If you prioritize Lure Modules, the ultra box is better. But if you are like a normal person and prefer raid passes and are willing to pay 2 gold per lure model, the Great Box is best.
EDIT: The bronze box "Special Box" is garbage, because if you take two of these, and compare it to the silver box, its 960 gold versus 980 gold, and for the 20 additional gold you get 10 lure modules. That is great, 2 gold per lure module. These normally cost 100. So please never buy the bronze box.